Compositions containing high levels of surfactant, such as concentrated dish washing compositions, hand soap compositions, shampoo compositions, laundry compositions, scrubbing compositions, etc. are well known and have typically provided in a liquid, a gel or a paste. While liquids and pastes may be useful in a variety of situations, such physical forms are no longer considered new and exciting. Also, while it is desirable to provide new and interesting physical forms, the use of the above compositions has typically been limited to application or pre-application of such liquids, gels and pastes into a substrate, and then the additional step of direct application to the desired surface.
While it is known to employ a foam-generating dispenser to make low-surfactant level compositions foam (i.e., body washes containing >12% surfactant), this approach has not to date succeeded for high surfactant microemulsion or protoemulsion compositions, as there is typically a direct correlation between increased surfactant levels and increased viscosity. Specifically, the rheology of high surfactant microemulsion or protoemulsion compositions makes it difficult to achieve acceptable foam without extremely turbulent and violent flow characteristics. As such turbulent flow characteristics often require excessive physical exertion or a highly-pressurized container, the practical result is that formulators are often required to lower the viscosity of their products so as to match the limitations of the foam-generating dispensers currently on the market. Therefore, this approach imparts an artificial, physical constraint upon formulators' freedom to achieve the best performing and/or lowest cost composition if foam-generation is desired.
Because of these physical constraints, solvent systems for such compositions may utilize solvents such as water, ethanol or propylene glycol to achieve the foam-generation desired. Glycerol is a polar compound known to have a relatively higher viscosity than water or ethanol or propylene glycol. It is derived from natural materials such as triglycerides and provides a non-petroleum derived materials useful in microemulsion and protoemulsions having high surfactant levels. Use of glycerol and/or propylene glycol in oil-in-water microemulsions is discussed in U.S. Pat. No. 6,008,180 and U.S. Pat. No. 6,121,228 as an optional solubilizing agent.
Accordingly, the need exists for a foam-generating dispenser which is able to produce foam from a high surfactant microemulsion or protoemulsion composition and to provide improved cleaning of surfaces such as dishes. The need further exists for a foam-generating dispenser which may produce such foam, without the need for excessive physical exertion, and/or the need to use an aerosol propellant with the use of a petroleum-derived solvent, such as glycerol.